WO2020129357A1 - Wavelength conversion member, optical device, projector, and manufacturing method for wavelength conversion member - Google Patents

Abstract

This wavelength conversion member is provided with: a matrix including an inorganic material; a fluorescent body embedded in the matrix; and a plurality of filler particles that are embedded in the matrix and include a resin material. This wavelength conversion member enables inhibition of detachment of the fluorescent body.

Description

Wavelength conversion member, optical device, projector, and method for manufacturing wavelength conversion member

The present disclosure relates to a wavelength conversion member, an optical device, a projector, and a method for manufacturing the wavelength conversion member.

In recent years, an optical device equipped with an excitation light source and a wavelength conversion member has been developed. The wavelength conversion member has a phosphor embedded in a matrix. Light from the excitation light source is applied to the phosphor as excitation light, and fluorescence light having a wavelength longer than the wavelength of the excitation light is emitted from the phosphor. Attempts have been made to increase the brightness and output of light in this type of optical device.

Patent Document 1 discloses a wavelength conversion element in which zinc oxide (ZnO) is used as a matrix material. ZnO is an inorganic material having a refractive index close to that of many phosphors, and also has excellent translucency and thermal conductivity. According to the wavelength conversion element of Patent Document 1, light scattering at the interface between the phosphor and the ZnO matrix can be suppressed, and high light output can be achieved.

Japanese Patent No. 5672622

The wavelength conversion member includes a matrix containing an inorganic material, a phosphor embedded in the matrix, and a plurality of filler particles embedded in the matrix and containing a resin material.

-This wavelength conversion member can suppress the falling of the phosphor.

FIG. 1 is a schematic sectional view of a wavelength conversion member according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view of filler particles of the wavelength conversion member shown in FIG. FIG. 3A is a sectional view of a substrate used in the method of manufacturing the wavelength conversion member according to the first embodiment. FIG. 3B is a diagram showing a state in which the precursor of the phosphor portion is formed on the substrate shown in FIG. 3A. FIG. 4 is a schematic cross-sectional view of the wavelength conversion member according to the second embodiment of the present disclosure. FIG. 5 is a schematic sectional view of a wavelength conversion member according to the third embodiment of the present disclosure. FIG. 6 is a schematic sectional view of a wavelength conversion member according to the fourth embodiment of the present disclosure. FIG. 7 is a schematic sectional view of a wavelength conversion member according to the fifth embodiment of the present disclosure. FIG. 8 is a schematic sectional view of a reflective optical device using the wavelength conversion member of the present disclosure. FIG. 9 is a schematic sectional view of a transmission type optical device using the wavelength conversion member of the present disclosure. FIG. 10 is a schematic configuration diagram of an optical device according to a modified example of the present disclosure. 11 is a perspective view of a wavelength conversion member included in the optical device shown in FIG. FIG. 12 is a schematic configuration diagram of a projector using the optical device of the present disclosure. FIG. 13 is a perspective view of the projector shown in FIG. FIG. 14 is a schematic configuration diagram of a lighting device using the optical device of the present disclosure. FIG. 15A is a diagram showing a microscope image of the precursor of the phosphor portion of Example 2 before the vibration test is performed. FIG. 15B is a diagram showing a microscope image of the precursor of the phosphor portion of Example 2 after the vibration test was performed. FIG. 16A is a diagram showing a microscope image of the precursor of the phosphor portion of Example 3 before the vibration test is performed. FIG. 16B is a diagram showing a microscope image of the precursor of the phosphor portion of Example 3 after the vibration test was performed. 17A is a diagram showing a scanning electron microscope (SEM) image of a cross section of the wavelength conversion member of Example 2. FIG. FIG. 17B is an enlarged view of the filler particles shown in FIG. 17A. FIG. 18A is a diagram showing an SEM image of a cross section of the wavelength conversion member of Example 3. 18B is an enlarged view of filler particles of the wavelength conversion member shown in FIG. 18A. FIG. 18C is an enlarged view of another filler particle of the wavelength conversion member shown in FIG. 18A.

(Findings that form the basis of this disclosure)
The wavelength conversion member can be manufactured, for example, by forming a matrix after disposing the phosphor on the substrate. However, when the substrate vibrates while the phosphor is placed on the substrate, the phosphor may fall off the substrate. When the matrix of inorganic crystals is formed by the solution growth method, the phosphor may fall off from the substrate while the substrate is immersed in the solution for crystal growth. In particular, when the size of the phosphor is large, when the phosphor is piled up high, or when the range in which the phosphor is arranged is wide, the phosphor is likely to fall off the substrate.

In the wavelength conversion element disclosed in Patent Document 1, the phosphor may fall off during the production of the wavelength conversion element.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view of the wavelength conversion member 100 according to the first embodiment. As shown in FIG. 1, the wavelength conversion member 100 includes a phosphor portion 20. The phosphor part 20 has a matrix 21, a phosphor 22 and a plurality of filler particles 23. The phosphor 22 is composed of, for example, a plurality of particles 122. The particles 122 of the phosphor 22 and the plurality of filler particles 23 are embedded in the matrix 21. In other words, the particles 122 of the phosphor 22 and the plurality of filler particles 23 are dispersed in the matrix 21. The particles 122 of the phosphor 22 and the plurality of filler particles 23 are surrounded by the matrix 21.

The shape of the phosphor unit 20 is, for example, a layer shape. The thickness of the phosphor part 20 is, for example, 20 μm or more and 200 μm or less. The thickness of the phosphor part 20 may be larger than 50 μm. When the phosphor portion 20 has a layered shape, the area of the phosphor portion 20 in plan view is, for example, 0.5 mm ² or more and 1500 mm ² or less.

The wavelength conversion member 100 may further include the substrate 10. The substrate 10 supports the phosphor section 20. The phosphor section 20 is arranged on the substrate 10.

When the wavelength conversion member 100 is irradiated with the excitation light having the first wavelength band, the wavelength conversion member 100 converts a part of the excitation light into light having the second wavelength band and emits it. The wavelength conversion member 100 emits light having a wavelength longer than the wavelength of the excitation light. The second wavelength band is a band different from the first wavelength band. However, a part of the second wavelength band may overlap with the first wavelength band. The light emitted from the wavelength conversion member 100 may include not only the light emitted from the phosphor 22 but also the excitation light itself.

The substrate 10 has, for example, a substrate body 11 and a thin film 12. The thickness of the substrate 10 is larger than the thickness of the phosphor portion 20, for example. The substrate body 11 is made of stainless steel, a composite material of aluminum and silicon carbide (Al-SiC), a composite material of aluminum and silicon (Al-Si), a composite material of aluminum and carbon (Al-C), copper ( Cu), sapphire (Al ₂ O ₃ ), alumina, gallium nitride (GaN), aluminum nitride (AlN), silicon (Si), aluminum (Al), glass, quartz (SiO ₂ ), silicon carbide (SiC) and oxidation. Made of one material selected from the group consisting of zinc. The substrate body 11 containing copper (Cu) may further contain other elements such as tungsten (W) and molybdenum (Mo). The substrate body 11 is made of stainless steel, a composite material of aluminum and silicon carbide (Al-SiC), a composite material of aluminum and silicon (Al-Si), a composite material of aluminum and carbon (Al-C), and copper ( When at least one selected from the group consisting of Cu) is included, the substrate body 11 has a small thermal expansion coefficient. Composed of stainless steel, aluminum-silicon carbide composite material (Al-SiC), aluminum-silicon composite material (Al-Si), aluminum-carbon composite material (Al-C), and copper (Cu) The substrate 10 including at least one selected from the group is suitable for use as a projector. The substrate body 11 has a light-transmitting property of transmitting, for example, excitation light and light emitted from the phosphor 22. In this case, the wavelength conversion member 100 can be suitably used for a transmission type optical device. When the substrate 10 does not have a light-transmitting property, the wavelength conversion member 100 can be used in a reflective optical device. The substrate body 11 may have a mirror-polished surface.

The surface of the substrate body 11 may be covered with an antireflection film, a dichroic mirror, a metal reflection film, a reflection enhancing film, a protective film, or the like. The antireflection film is a film for preventing reflection of excitation light. The dichroic mirror may be composed of a dielectric multilayer film. The metal reflection film is a film for reflecting light and is made of a metal material such as silver or aluminum. The enhanced reflection film may be composed of a dielectric multilayer film. The protective film may be a film for physically or chemically protecting these films.

The thin film 12 functions as a base layer for forming the phosphor portion 20. When the matrix 21 of the phosphor part 20 is crystalline, the thin film 12 functions as a seed crystal in the crystal growth process of the matrix 21. That is, the thin film 12 is a single crystal thin film or a polycrystalline thin film. When the matrix 21 is composed of a ZnO single crystal or a ZnO polycrystal, the thin film 12 may be a ZnO single crystal thin film or a ZnO polycrystal thin film. Elements other than Zn may be added to the thin film 12. When an element such as Ga, Al or B is added to the thin film 12, the thin film 12 has a low electric resistance. The thin film 12 may include an amorphous Zn compound or amorphous ZnO. The thickness of the thin film 12 may be 5 nm or more and 2000 nm or less, or 5 nm or more and 200 nm or less. The thinner the thin film 12 is, the shorter the distance between the phosphor unit 20 and the substrate 10, and thus the better thermal conductivity is obtained. However, when the substrate body 11 can exhibit the function of the seed crystal, the thin film 12 may be omitted and the phosphor portion 20 may be in direct contact with the substrate body 11. For example, when the substrate body 11 is made of crystalline GaN or crystalline ZnO, the matrix 21 made of crystalline ZnO can be directly formed on the substrate body 11. Even when the matrix 21 is not crystalline, the thin film 12 may be omitted and the phosphor portion 20 may be in direct contact with the substrate body 11.

In the phosphor unit 20, particles 122 of the phosphor 22 are dispersed in the matrix 21. In FIG. 1, the particles 122 of the phosphor 22 are separated from each other. However, the particles 122 of the phosphor 22 may be in contact with each other. The filler particles 23 may be located between the two particles 122 of the phosphor 22 or may be located between the particles 122 of the phosphor 22 and the substrate 10. The filler particles 23 are in contact with the particles 122 of the phosphor 22, for example. Specifically, the filler particles 23 are adhered to the particles 122 of the phosphor 22. In the present disclosure, "adhesion" means the state where two objects are attached to each other. In the present disclosure, “adhesion” is used as a term including “adhesion”, “adhesion”, “adhesion” and the like. In the wavelength conversion member 100, for example, (i) one filler particle 23 is adhered to both two particles 122 of the phosphor 22, (ii) one filler particle 23 is the particle 122 of the phosphor 22 and the substrate. 10 is adhered, and (iii) one filler particle 23 is adhered to both the particles 122 of the phosphor 22 and the matrix 21. At least one requirement selected from the group consisting of: The plurality of filler particles 23 may be separated from each other or may be in contact with each other. The plurality of filler particles 23 may have a lump shape by being adhered to each other. The filler particles 23 may adhere to the particles 122 of the phosphor 22 to partially cover the surface of the particles 122 of the phosphor 22. The particles 122 of the phosphor 22 and the filler particles 23 may be stacked like a stone wall.

The material of the phosphor 22 is not particularly limited. Various fluorescent substances may be used as the material of the phosphor 22. _{Specifically, Y 3 Al 5 O1 2:} Ce (YAG), Y 3 (Al, Ga) 5 O 12: Ce (GYAG), Lu 3 Al 5 O 12: Ce (LuAG), (Si, Al) ₆ (O,N) ₈ :Eu(β-SiAlON), (La,Y) ₃ Si ₆ N ₁₁ :Ce(LYSN), Lu ₂ CaMg ₂ Si ₃ O ₁₂ :Ce(LCMS) and other fluorescent substances are used. Can be done. The phosphor 22 may further include a material other than the fluorescent substance. Examples of the other material include a material having a light-transmitting property. Examples of the translucent material include glass, SiO ₂ , Al ₂ O _{3 and the} like. The phosphor 22 may include a plurality of types of phosphors having different compositions. The material of the phosphor 22 is selected according to the chromaticity of the light to be emitted from the wavelength conversion member 100.

The average particle diameter of the particles 122 of the phosphor 22 is, for example, in the range of 0.1 μm or more and 50 μm or less. The average particle size of the particles 122 of the phosphor 22 may be larger than 10 μm. The average particle size of the particles 122 of the phosphor 22 can be specified, for example, by the following method. First, the cross section of the wavelength conversion member 100 is observed with a scanning electron microscope. In the obtained electron microscope image, the area of the particles 122 of the specific phosphor 22 is calculated by image processing. The diameter of a circle having the same area as the calculated area is regarded as the particle diameter (particle diameter) of the particles 122 of the specific phosphor 22. The particle diameters of the particles 122 of the phosphor 22 of an arbitrary number (for example, 50) are calculated, and the average value of the calculated values is regarded as the average particle diameter of the particles 122 of the phosphor 22. In the present disclosure, the shape of the particles 122 of the phosphor 22 is not limited. The shape of the particles 122 of the phosphor 22 may be spherical, ellipsoidal, scaly, or fibrous. In the present disclosure, the method for measuring the average particle size is not limited to the above method.

In the phosphor part 20, the filler particles 23 are dispersed in the matrix 21. The filler particles 23 include a resin material. The filler particles 23 may include a resin material as a main component. The “main component” means a component contained in the filler particles 23 most in a weight ratio. The filler particles 23 are substantially made of a resin material, for example. "Consisting essentially of" means excluding other ingredients that modify the essential characteristics of the material referred to. However, the filler particles 23 may contain impurities in addition to the resin material. The resin material may include a thermoplastic resin or a thermosetting resin. The thermoplastic resin includes, for example, at least one selected from the group consisting of polystyrene (PS), methacrylic resin and polycarbonate (PC). The methacrylic resin contains, for example, polymethylmethacrylate (PMMA). When the filler particles 23 contain a thermoplastic resin, the strength of the wavelength conversion member 100 is improved. The thermoplastic resin may include a thermoplastic elastomer. Examples of the thermoplastic elastomer include styrene elastomer, olefin elastomer, vinyl chloride elastomer, urethane elastomer, ester elastomer and amide elastomer. Elastomer means a material having rubber elasticity.

The thermosetting resin includes, for example, at least one selected from the group consisting of silicone resin and epoxy resin. The silicone resin is, for example, a polymer compound having a siloxane bond. The silicone resin has, for example, a siloxane bond in the main skeleton. Examples of the silicone resin include dimethylpolysiloxane and polyorganosilsesquioxane. Polyorganosilsesquioxane has, for example, a structure in which three-dimensional network cross-links are formed by siloxane bonds. This structure is represented by, for example, the general formula (RSiO _3/2 ) _n . In this general formula, R is, for example, an alkyl group.

The thermosetting resin may include a thermosetting elastomer. Examples of thermosetting elastomers include urethane rubber, silicone rubber, and fluororubber. Silicone rubber is a silicone resin having rubber elasticity. Silicone rubber has, for example, a structure in which dimethylpolysiloxane is crosslinked.

As filler particles containing silicone resin or silicone rubber, for example, KMP series, KSP series, X-52 series, etc. are commercially available from Shin-Etsu Chemical Co., Ltd., EP series, TREFIL series, 30- 424 Additive is commercially available. When the resin material contains a polymer compound having a siloxane bond, the filler particles 23 have excellent heat resistance.

The filler particles 23 may have a surface 24 modified with a functional group. At this time, the filler particles 23 have excellent dispersibility. That is, the surface 24 modified with the functional group can suppress the aggregation of the filler particles 23. Examples of the functional group that modifies the surface 24 include an epoxy group, a (meth)acryloyl group, and a methyl group.

The average particle diameter of the filler particles 23 may be 0.1 μm or more and 20 μm or less, or 1.0 μm or more and 10 μm or less. The average particle size of the filler particles 23 is smaller than the average particle size of the particles 122 of the phosphor 22, for example. The ratio (D2/D1) of the average particle diameter D2 of the filler particles 23 to the average particle diameter D1 of the particles 122 of the phosphor 22 is, for example, 0.01 or more and 0.90 or less. The average particle size of the filler particles 23 can be measured by the same method as the average particle size of the particles 122 of the phosphor 22. The value of V2/(V1+V2) defined by the total volume V1 of the particles 122 of the phosphor 22 and the total volume V2 of the filler particles 23 may be 0.01 or more and 0.70 or less, and may be 0.05 or less. It may be 0.16 or less. The specific gravity of the filler particles 23 is, for example, 0.5 g/cm ³ or more and 1.5 g/cm ³ or less. The total volume V1 of the particles 122 of the phosphor 22 is the total volume of the phosphor 22.

In the present disclosure, the shape of the filler particles 23 is not particularly limited. The shape of the filler particles 23 may be spherical, ellipsoidal, scaly, or fibrous. FIG. 2 shows an example of a cross section of the filler particles 23. As shown in FIG. 2, the filler particles 23 may have a core 30 and a shell 31 that covers the core 30. The shell 31 may cover the entire surface of the core 30 or may partially cover the surface of the core 30. The shell 31 is in contact with the core 30, for example. The composition of the core 30 is different from that of the shell 31, for example. As an example, the core 30 is made of silicone rubber, and the shell 31 is made of a silicone resin other than silicone rubber. The shape of the core 30 is, for example, spherical. In FIG. 2, the shell 31 is composed of a plurality of particles. However, the shell 31 may have a layered shape. The average particle size of the particles forming the shell 31 is, for example, 1 nm or more and 1 μm or less. When the filler particles 23 have the shell 31, the filler particles 23 have excellent dispersibility. That is, the shell 31 can suppress aggregation of the filler particles 23.

When the resin material contains a thermoplastic elastomer or a thermosetting elastomer, the filler particles 23 have rubber elasticity. The rubber hardness of the filler particles 23 may be 10 or more and 90 or less, or 30 or more and 75 or less. The rubber hardness of the filler particles 23 can be measured as follows, for example, by a method according to JIS (Japanese Industrial Standard) K6253-3:2012. First, a test piece having the same composition as the filler particles 23 is prepared. The shape of the test piece is specified in JIS K6253-3:2012. For example, the rubber hardness of the test piece is measured by a method using a type A durometer specified in JIS K6253-3:2012. The rubber hardness of the obtained test piece can be regarded as the rubber hardness of the filler particles 23. However, in the present disclosure, the method for measuring rubber hardness is not limited to the above method.

The glass transition temperature Tg of the filler particles 23 is not particularly limited. When the filler particles 23 contain a thermoplastic resin, the glass transition temperature Tg of the filler particles 23 may be, for example, 50° C. or higher and 300° C. or lower. When the filler particles 23 contain a thermosetting elastomer, the glass transition temperature Tg of the filler particles 23 may be 30° C. or lower, or 0° C. or lower. As an example, the glass transition temperature Tg of silicone rubber is -125°C. The lower limit value of the glass transition temperature Tg of the filler particles 23 is, for example, −273° C. When the glass transition temperature Tg of the filler particles 23 is lower than room temperature, the filler particles 23 have excellent adhesiveness at room temperature. In the present disclosure, room temperature means 25° C. or higher and 30° C. or lower. The glass transition temperature Tg of the filler particles 23 can be measured, for example, by using a differential scanning calorimeter (DSC) by a method according to JIS K7121:1987. With respect to the filler particles 23 containing a silicone rubber or the like and having a glass transition temperature Tg of 0° C. or lower, when the specific glass transition temperature Tg of the filler particles 23 is specified, the glass transition temperature Tg is 0° C. or lower. A DSC capable of measuring is used. However, in the present disclosure, the method for measuring the glass transition temperature Tg is not limited to the above method.

When the filler particles 23 are irradiated with the excitation light, the filler particles 23 do not emit fluorescent light or emit only fluorescent light having a negligible intensity. The light absorption rate of the filler particles 23 is not particularly limited. The absorptance of the filler particles 23 with respect to light having a wavelength of 550 nm is preferably 25% or less, more preferably 10% or less, and further preferably 1% or less. The filler particles 23 may not substantially absorb light having a wavelength of 550 nm. The absorptance of the filler particles 23 with respect to light having a wavelength of 450 nm is preferably 25% or less, more preferably 10% or less, and further preferably 1% or less. The filler particles 23 do not have to substantially absorb light having a wavelength of 450 nm.

The light absorptance of the filler particles 23 can be measured using, for example, a commercially available absolute PL quantum yield measuring device. The absolute PL quantum yield measuring device is a device that measures the absolute value of the emission quantum yield of a sample such as a fluorescent material for a light emitting diode (LED) by a photoluminescence (PL) method. The emission quantum yield of a sample can be measured by the following method using a sample holder for measurement and a petri dish for measuring powder. First, the sample is placed inside the petri dish. Next, this petri dish is placed inside the integrating sphere. A sample is irradiated with excitation light having a specific wavelength that is separated from a xenon light source. At this time, the emission quantum yield of the sample can be measured by measuring the light emitted from the sample. The light absorption rate of the filler particles 23 can be measured, for example, by the following method. First, an empty petri dish on which no sample is placed is placed inside the integrating sphere. The emission quantum yield is measured on an empty petri dish. Thereby, the number of photons of the excitation light can be measured in the state where the sample is not arranged. Next, a petri dish on which the filler particles 23 are arranged is arranged inside the integrating sphere as a sample. The emission quantum yield of the filler particles 23 is measured. Thereby, the number of photons of the excitation light in the state where the filler particles 23 are arranged can be measured. From these measurement results, the ratio of the number of photons absorbed by the filler particles 23 to the number of photons of the excitation light with which the filler particles 23 are irradiated can be calculated. This ratio can be regarded as the light absorption rate of the filler particles 23. The petri dish is made of, for example, synthetic quartz that absorbs little light in the measurement wavelength range. The bottom surface of the dish has, for example, a circular shape in plan view. The diameter of the bottom surface of the dish in plan view is, for example, about 17 mm. The thickness of the petri dish is, for example, about 5 mm. The dish has, for example, a lid.

When the filler particles 23 are heated at an ambient temperature of 200° C. for 24 hours, the absorptance of the filler particles 23 with respect to light having a wavelength of 550 nm is preferably 25% or less, more preferably 10% or less, and further preferably Is 1% or less. When the filler particles 23 are heated at an ambient temperature of 240° C. for 24 hours, the absorptivity of the filler particles 23 for light having a wavelength of 550 nm is preferably 25% or less, more preferably 10% or less, and further preferably Is 1% or less.

The matrix 21 includes an inorganic material. The inorganic material may include inorganic crystals. Inorganic materials, for _{example, ZnO, SiO 2, Al 2} O 3, SnO 2, TiO 2, PbO, B 2 O 3, P 2 O 5, TeO 2, V 2 O 5, Bi 2 O 3, Ag 2 O , Tl ₂ O and BaO. The matrix 21 may include glass as an inorganic material.

The matrix 21 contains, for example, zinc oxide (ZnO). ZnO is suitable for the material of the matrix 21 from the viewpoint of transparency and thermal conductivity. ZnO has high thermal conductivity. Therefore, when ZnO is used as the material of the matrix 21, the heat of the phosphor portion 20 can be easily released to the outside (mainly the substrate 10). Thereby, the temperature rise of the phosphor 22 can be suppressed. The matrix 21 may contain ZnO as a main component. The matrix 21 is substantially made of ZnO, for example. However, the matrix 21 may contain impurities in addition to ZnO.

Specifically, ZnO as a material of the matrix 21 is a ZnO single crystal or a ZnO polycrystal. ZnO has a wurtzite crystal structure. When the matrix 21 is formed by crystal growth, the matrix 21 has a crystal structure according to the crystal structure of the thin film 12, for example. That is, when a polycrystal of ZnO oriented along the c-axis is used as the thin film 12, the matrix 21 has a polycrystal of ZnO oriented along the c-axis. “ZnO oriented in the c-axis” means that the plane parallel to the main surface of the substrate 10 is the c-plane. The “main surface” means the surface of the substrate 10 having the largest area. When the matrix 21 includes a ZnO polycrystal oriented in the c-axis, light scattering is suppressed inside the phosphor portion 20, and a high light output can be achieved.

The c-axis oriented ZnO polycrystal includes a plurality of columnar crystal grains oriented along the c-axis. In a c-axis oriented ZnO polycrystal, there are few crystal grain boundaries in the c-axis direction. “The columnar crystal grains are oriented in the c-axis” means that the growth of ZnO in the c-axis direction is faster than the growth of ZnO in the a-axis direction, and vertically long ZnO crystal grains are formed on the substrate 10. Means that The c-axis of ZnO crystal grains is parallel to the normal direction of the substrate 10. In other words, the c-axis of the ZnO crystal grains is parallel to the normal line direction of the surface of the phosphor section 20 that receives the excitation light. Whether or not ZnO is a c-axis oriented crystal can be confirmed by X-ray diffraction (XRD) measurement (2θ/ω scan). In the diffraction peak of ZnO obtained from the XRD measurement result, when the diffraction peak due to the c-plane of ZnO has a higher intensity than the diffraction peak due to other than the c-plane of ZnO, ZnO is a c-axis oriented crystal. It can be judged that there is. WO 2013/172025 discloses in detail a matrix constituted by c-axis oriented ZnO polycrystals.

The luminous efficiency of the wavelength conversion member 100 is preferably 85% or more, more preferably 90% or more. In the present disclosure, the light emission efficiency of the wavelength conversion member 100 means that, out of the excitation light irradiated on the wavelength conversion member 100, the wavelength conversion member 100 radiates the number of photons of the excitation light absorbed by the wavelength conversion member 100. It means the ratio of the number of photons of fluorescent light. The luminous efficiency of the wavelength conversion member 100 can be measured by, for example, a multi-channel spectroscope. The emission efficiency of the wavelength conversion member 100 is a value when the wavelength conversion member 100 is irradiated with excitation light having an energy density of ² W/mm ² .

Further, when the wavelength conversion member 100 is heated at an ambient temperature of 240° C. for 24 hours, the light emission efficiency of the wavelength conversion member 100 is preferably 85% or more, more preferably 90% or more.

Next, a method of manufacturing the wavelength conversion member 100 will be described.

First, a method of manufacturing the substrate 10 will be described. FIG. 3A shows a cross section of the substrate 10 used in the method of manufacturing the wavelength conversion member 100. For example, a crystalline ZnO thin film is formed as the thin film 12 on the substrate body 11. As a method for forming a ZnO thin film, vapor phase film forming methods such as vapor deposition method, electron beam vapor deposition method, reactive plasma vapor deposition method, ion assisted vapor deposition method, sputtering method and pulse laser deposition method are used. The thin film 12 may be formed by the following method. First, a sol containing a precursor such as zinc alkoxide is prepared. The sol is applied to the substrate body 11 by a printing method to form a coating film. Next, the thin film 12 is obtained by heating the coating film. The thin film 12 may be a ZnO single crystal thin film or a ZnO polycrystalline thin film.

Next, a method for producing the precursor 25 of the phosphor part 20 on the substrate 10 (on the thin film 12) will be described. FIG. 3B is a diagram showing a state in which the precursor 25 of the phosphor unit 20 is formed on the substrate shown in FIG. 3A. First, the particles 122 of the phosphor 22 and the filler particles 23 are arranged on the substrate 10. For example, a dispersion liquid containing the particles 122 of the phosphor 22 and the filler particles 23 is prepared. The substrate 10 is placed in the dispersion liquid, and the particles 122 of the phosphor 22 and the filler particles 23 are deposited on the substrate 10 by using an electrophoretic method. As a result, the particles 122 of the phosphor 22 and the filler particles 23 can be arranged on the substrate 10. Alternatively, the particles 122 of the phosphor 22 and the filler particles 23 can be arranged on the substrate 10 by placing the substrate 10 in the dispersion liquid and allowing the particles 122 of the phosphor 22 and the filler particles 23 to settle. Alternatively, the particles 122 of the phosphor 22 and the filler particles 23 can be arranged on the substrate 10 by using a coating liquid containing the particles 122 of the phosphor 22 and the filler particles 23 and by a thick film forming method such as a printing method.

Next, the particles 122 of the phosphor 22 are fixed to the substrate 10 by the filler particles 23. For example, when the filler particles 23 are heated, the resin contained in the filler particles 23 is softened. This allows the filler particles 23 to adhere to both the particles 122 of the phosphor 22 and the substrate 10 and fix the particles 122 of the phosphor 22 to the substrate 10. When the filler particles 23 have rubber elasticity, the contact area between the filler particles 23 and the particles of the phosphor 22 is wide. At this time, the filler particles 23 can firmly fix the particles 122 of the phosphor 22. The filler particles 23 may not be directly adhered to the substrate 10, but may be adhered to both the particles 122 of the phosphor 22 fixed to the substrate 10 and the particles 122 of the other phosphor 22. When the filler particles 23 have adhesiveness at room temperature, the heat treatment of the filler particles 23 may be omitted. The precursor 25 is obtained by fixing the particles 122 of the phosphor 22 to the substrate 10 with the filler particles 23. The precursor 25 has a porous structure composed of filler particles 23 and particles 122 of the phosphor 22. In other words, the surface of the thin film 12 facing the precursor 25 has both a region covered with the filler particles 23 and a region not covered with the filler particles 23.

The conditions for heating the filler particles 23 are not particularly limited. The ambient temperature when heating the filler particles 23 may be 50° C. or higher and 400° C. or lower, or 100° C. or higher and 300° C. or lower. The heating time of the filler particles 23 may be 5 minutes or more and 5 hours or less.

Next, the matrix 21 is formed so that the filler particles 23 and the particles 122 of the phosphor 22 are embedded in the matrix 21. Thereby, the phosphor part 20 can be manufactured. When the matrix 21 contains glass, the phosphor part 20 can be manufactured by the following method. First, a sol containing silicon alkoxide is prepared. The sol is applied on the precursor 25. This allows the porous structure of the precursor 25 to be filled with the sol. The sol is gelled and fired. Thereby, the phosphor part 20 is obtained. Even when the matrix 21 contains an inorganic material other than glass, the phosphor part 20 can be formed using a sol containing an alkoxide, as in the above method. Further, by filling the inside of the precursor 25 with a low-melting glass containing an inorganic material, the phosphor portion 20 can be formed.

When the matrix 21 contains zinc oxide, a solution growth method using a solution containing Zn ions can be used as a method of forming the matrix 21. The solution growth method includes a chemical solution deposition method that is performed under atmospheric pressure, a hydrothermal synthesis method that is performed under a pressure higher than atmospheric pressure, and an electrolytic deposition method that applies voltage or current. Electrochemical deposition) or the like is used. As a solution for crystal growth, for example, an aqueous solution of zinc nitrate (Zinc nitrate: Zn(NO ₃ ) ₂ ) containing hexamethylenetetramine (C ₆ H ₁₂ N ₄ ) is used. The pH of the aqueous solution of zinc nitrate is, for example, 5 or more and 7 or less. The matrix 21 is crystal-grown on the thin film 12 by the solution growth method. The matrix 21 also undergoes crystal growth inside the porous structure of the precursor 25. As a result, the phosphor section 20 is obtained. Details of the solution growth method are disclosed in, for example, Japanese Patent Laid-Open No. 2004-315342.

The manufacturing method of the present embodiment may further include removing the substrate 10 from the wavelength conversion member 100 after forming the matrix 21. For example, the substrate body 11 and the thin film 12 may be separated by heating the substrate body 11. Thereby, the substrate 10 can be removed from the wavelength conversion member 100. The substrate body 11 and the wavelength conversion member 100 may be separated by focusing the laser light on the interface between the substrate body 11 and the thin film 12.

In the precursor 25, the particles 122 of the phosphor 22 are fixed to the substrate 10 by the filler particles 23. Therefore, it is possible to prevent the particles 122 of the phosphor 22 from falling off the substrate 10 before the matrix 21 is formed. That is, in the wavelength conversion member 100 of this embodiment, the particles 122 of the phosphor 22 are prevented from falling off. Thereby, the yield of the wavelength conversion member 100 can be improved. Since the particles 122 of the phosphor 22 are prevented from falling off, the phosphor part 20 of the wavelength conversion member 100 contains the particles 122 of the phosphor 22 in a practically sufficient amount.

(Embodiment 2)
FIG. 4 is a schematic sectional view of the wavelength conversion member 110 according to the second embodiment. As shown in FIG. 4, the phosphor 22 of the wavelength conversion member 110 has the shape of a block 222. Of the plurality of phosphors 22 included in the phosphor unit 20, some of the phosphors 22 are partially exposed from the phosphor unit 20. Except for the above, the structure of the wavelength conversion member 110 is the same as the structure of the wavelength conversion member 100 of the first embodiment. Therefore, the elements common to the wavelength conversion member 100 of the first embodiment and the wavelength conversion member 110 of the present embodiment are denoted by the same reference numerals, and the description thereof may be omitted. That is, the following description of each embodiment can be applied to each other as long as there is no technical contradiction. Further, the respective embodiments may be combined with each other as long as there is no technical contradiction.

The block 222 of the phosphor 22 has, for example, a polyhedron shape. The shape of the phosphor 22 may be a rectangular parallelepiped shape or a cubic shape. The shape of the phosphor 22 may be a lump. The block 222 of the block-shaped phosphor 22 can be produced, for example, by crushing a plate-shaped phosphor. The size of the block 222 of the phosphor 22 may be larger than the size of the phosphor particles 122.

In the wavelength conversion member 110, a part of the plurality of phosphors 22 is partially exposed from the side surface of the phosphor part 20. The phosphor 22 may be exposed from the upper surface of the phosphor unit 20. That is, the phosphor 22 may be partially embedded in the matrix 21, or may not be completely embedded.

(Embodiment 3)
In the wavelength conversion member 110 of the second embodiment, the plurality of phosphors 22 may be regularly arranged. FIG. 5 is a schematic sectional view of the wavelength conversion member 120 according to the third embodiment. As shown in FIG. 5, in the wavelength conversion member 120, the plurality of phosphors 22 are arranged at equal intervals in the direction orthogonal to the thickness direction of the phosphor part 20. The upper surface and the lower surface of the phosphor 22 may extend in a direction orthogonal to the thickness direction of the phosphor unit 20. The upper surface and the lower surface of the phosphor 22 may be parallel to each other. The side surface of the phosphor 22 may extend in the thickness direction of the phosphor unit 20. The side surfaces of the phosphor 22 may be parallel to each other.

The filler particles 23 are adhered to both the lower surface of the phosphor 22 and the substrate 10, for example. The filler particles 23 may be adhered to both the side surface of the phosphor 22 and the side surface of another phosphor 22.

In the wavelength conversion member 120, some of the plurality of phosphors 22 may be exposed from the phosphor part 20. The phosphor 22 may be exposed from the upper surface of the phosphor unit 20. That is, the phosphor 22 may be partially embedded in the matrix 21, and may not be completely embedded.

(Embodiment 4)
FIG. 6 is a schematic sectional view of the wavelength conversion member 130 according to the fourth embodiment. As shown in FIG. 6, the phosphor part 20 of the wavelength conversion member 130 has one phosphor 22. The shape of the phosphor 22 is, for example, a plate shape. The size of the plate-shaped phosphor 22 may be larger than the size of the phosphor particles 122. Except for the above, the structure of the wavelength conversion member 130 is the same as the structure of the wavelength conversion member 100 according to the first embodiment.

The phosphor 22 may have a plurality of holes 22a. The plurality of holes 22a are, for example, through holes that penetrate the phosphor 22 in the thickness direction. The matrix 21 is filled in each of the plurality of holes 22a, for example. In FIG. 6, hatching of the matrix 21 is omitted for the sake of explanation.

The plurality of holes 22a can be formed, for example, by irradiating the plate-shaped phosphor 22 with a laser beam or an ion beam. The plurality of holes 22a can also be formed, for example, by etching the plate-shaped phosphor 22.

The filler particles 23 are adhered to both the lower surface of the phosphor 22 and the substrate 10, for example. The phosphor unit 20 may include a plurality of plate-shaped phosphors 22. In the phosphor unit 20, a plurality of plate-shaped phosphors 22 may be arranged in the thickness direction of the phosphor unit 20. At this time, the filler particles 23 may be bonded to each of the upper surface of the phosphor 22 and the lower surface of the other phosphor 22.

In the wavelength conversion member 130, the upper surface of the plate-shaped phosphor 22 may be exposed from the phosphor part 20. The side surface of the plate-shaped phosphor 22 may be exposed from the phosphor portion 20. That is, the plate-shaped phosphor 22 may be partially embedded in the matrix 21 or may not be completely embedded.

(Embodiment 5)
In the wavelength conversion member 130 according to the fourth embodiment, the plurality of holes 22a need not be through holes. FIG. 7 is a schematic sectional view of the wavelength conversion member 140 according to the fifth embodiment. As shown in FIG. 7, in the wavelength conversion member 140, each of the plurality of holes 22 a is opened only on the lower surface of the phosphor 22 and is not opened on the upper surface. The plurality of holes 22a may be opened only on the upper surface of the phosphor 22 and may be opened on the lower surface.

In the wavelength conversion member 140, the upper surface of the plate-shaped phosphor 22 may be exposed from the phosphor unit 20. The side surface of the plate-shaped phosphor 22 may be exposed from the phosphor portion 20. That is, the plate-shaped phosphor 22 may be partially embedded in the matrix 21 or may not be completely embedded.

(Embodiment of optical device)
FIG. 8 is a schematic cross-sectional view of the optical device 200 according to the embodiment. As shown in FIG. 8, the optical device 200 includes the wavelength conversion member 100 and the excitation light source 40. The excitation light source 40 emits excitation light. The wavelength conversion member 100 is arranged on the optical path along which the excitation light emitted from the excitation light source 40 travels. The phosphor portion 20 of the wavelength conversion member 100 is located between the excitation light source 40 and the substrate 10 of the wavelength conversion member 100. The optical device 200 is a reflective optical device. Instead of the wavelength conversion member 100, the wavelength conversion member 110 described with reference to FIG. 4, the wavelength conversion member 120 described with reference to FIG. 5, the wavelength conversion member 130 described with reference to FIG. The wavelength conversion member 140 described with reference to FIG. It is also possible to use the combination of the wavelength conversion members 100, 110, 120, 130, 140 in the optical device 200.

The excitation light source 40 is typically a semiconductor light emitting element. The semiconductor light emitting element is, for example, a light emitting diode (LED), a super luminescent diode (SLD) or a laser diode (LD).

The excitation light source 40 may be configured by one LD or may be configured by a plurality of LDs. The plurality of LDs may be optically coupled. The excitation light source 40 emits blue light, for example. In the present disclosure, blue light is light having a peak wavelength of 420 nm or more and 470 nm or less.

The optical device 200 further includes an optical system 50. The optical system 50 may be located on the optical path of the excitation light emitted from the excitation light source 40. The optical system 50 includes optical components such as a lens, a mirror, and an optical fiber.

(Modification of optical device)
The phosphor unit 20 may not be located between the excitation light source 40 and the substrate 10 of the wavelength conversion member 100. FIG. 9 is a schematic cross-sectional view of an optical device 210 according to the modification. In the optical device 210 of FIG. 9, the excitation light source 40 faces the substrate 10 of the wavelength conversion member 100. In the optical device 210, the substrate 10 is transparent to the excitation light. The excitation light passes through the substrate 10 and reaches the phosphor unit 20. The optical device 210 is a transmissive optical device.

(Another modification of the optical device)
FIG. 10 is a schematic cross-sectional view of an optical device 220 according to another modification. As shown in FIG. 10, the optical device 220 of this embodiment includes a plurality of excitation light sources 40 and the wavelength conversion member 100. In FIG. 10, the phosphor section 20 of the wavelength conversion member 100 is located between each of the plurality of excitation light sources 40 and the substrate 10 of the wavelength conversion member 100. The plurality of excitation light sources 40 face the phosphor unit 20 of the wavelength conversion member 100. The optical device 220 is suitable for use as a projector.

FIG. 11 is a perspective view of the wavelength conversion member 100 included in the optical device 220. As shown in FIG. 11, the wavelength conversion member 100 of the optical device 220 has a wheel shape. Specifically, the substrate 10 of the wavelength conversion member 100 of the optical device 220 has a disc shape. The substrate 10 has a through hole 13 and a transparent portion 14. The through hole 13 extends in the thickness direction of the substrate 10. The through hole 13 is located at the center of a virtual circle defined by the outer peripheral surface of the substrate 10, for example. The light transmitting portion 14 that transmits light has an arc shape, that is, an annular fan shape. The translucent part 14 may be in contact with the phosphor part 20. The transparent portion 14 is, for example, a through hole. The translucent portion 14 may be made of transparent resin or glass. The translucent portion 14 may be made of a translucent material such as sapphire or quartz.

The phosphor portion 20 has an arc shape, that is, an annular fan shape. The phosphor body 20 and the translucent portion 14 are arranged along an imaginary circle defined by the outer peripheral surface of the phosphor body 20. The phosphor portion 20 partially covers the main surface of the substrate 10. In the optical device 220, the wavelength conversion member 100 may include a plurality of phosphor parts 20. A plurality of phosphor parts 20 may be arranged along an imaginary circle defined by the outer peripheral surface of the specific phosphor part 20. The phosphors 22 included in the plurality of phosphor parts 20 may have different compositions from each other.

As shown in FIG. 10, the optical device 220 further includes a motor 60. The wavelength conversion member 100 is arranged on the motor 60. Specifically, the shaft of the motor 60 is inserted into the through hole 13 of the substrate 10. The wavelength conversion member 100 is fixed to the motor 60 by a fixing member such as a screw. The wavelength conversion member 100 is rotated by the motor 60, and the wavelength conversion member 100 is irradiated with the excitation light emitted from the plurality of excitation light sources 40. Thereby, it is possible to prevent the excitation light from being locally applied to the phosphor portion 20. Therefore, it is possible to prevent the temperature of the phosphor unit 20 from rising due to the excitation light and the fluorescence light.

The optical device 220 further includes a collimator lens 51, a dichroic mirror 52, lenses 53 and 54, and reflection mirrors 55, 56 and 57. The collimator lens 51, the dichroic mirror 52, and the lens 53 are located between each of the plurality of excitation light sources 40 and the wavelength conversion member 100. The collimating lens 51, the dichroic mirror 52, and the lens 53 are arranged in this order on the optical path where the excitation light emitted from the plurality of excitation light sources 40 travels. The lens 54, the reflection mirrors 55, 56, 57 and the dichroic mirror 52 are arranged in this order on the optical path along which the excitation light transmitted through the wavelength conversion member 100 travels.

The collimator lens 51 collects the excitation light emitted from the plurality of excitation light sources 40. Parallel light is obtained by the collimator lens 51. The dichroic mirror 52 can transmit the excitation light and efficiently reflect the light emitted from the wavelength conversion member 100. The lens 53 collects the excitation light and the light emitted from the wavelength conversion member 100. The lens 54 collects the excitation light that has passed through the wavelength conversion member 100. Parallel light is obtained by the lens 54. Each of the reflection mirrors 55, 56, 57 reflects the excitation light.

The optical device 220 further includes a heat sink 41. The heat sink 41 is in contact with the plurality of excitation light sources 40. With the heat sink 41, the heat of the plurality of excitation light sources 40 can be easily released to the outside. As a result, it is possible to prevent the temperatures of the plurality of pumping light sources 40 from rising, and thus it is possible to suppress a decrease in energy conversion efficiency in the plurality of pumping light sources 40.

Next, the operation of the optical device 220 will be described.

First, a plurality of excitation light sources 40 emit excitation light. The excitation light is condensed by the collimator lens 51 and converted into parallel light. Next, the excitation light passes through the dichroic mirror 52 and is further condensed by the lens 53. The lens 53 can adjust the spot diameter of the excitation light that should be incident on the phosphor unit 20. Next, the excitation light enters the wavelength conversion member 100. The wavelength conversion member 100 is rotated by the motor 60. Therefore, the operation of the optical device 220 has a period in which the excitation light is incident on the phosphor unit 20 and a period in which the excitation light is transmitted through the light transmitting unit 14. The wavelength conversion member 100 emits light having a wavelength longer than the wavelength of the excitation light while the excitation light is incident on the phosphor unit 20. The excitation light is incident on the lens 54 during the period in which the excitation light is transmitted through the transparent portion 14. The light emitted from the wavelength conversion member 100 is condensed by the lens 53 and converted into parallel light. The light emitted from the wavelength conversion member 100 is reflected by the dichroic mirror 52 and sent to the outside of the optical device 220.

When the excitation light passes through the translucent portion 14, the excitation light is condensed by the lens 54 and converted into parallel light. The excitation light that has passed through the lens 54 is reflected by the reflection mirrors 55, 56 and 57. Next, the excitation light passes through the dichroic mirror 52. As a result, the excitation light is sent to the outside of the optical device 220. At this time, the excitation light mixes with the light emitted from the wavelength conversion member 100.

(Embodiment of projector)
FIG. 12 is a schematic configuration diagram of the projector 500 according to the present embodiment. As shown in FIG. 12, the projector 500 includes an optical device 220, an optical unit 300, and a controller 400. The optical unit 300 converts the light emitted from the optical device 220 and projects an image or video on an object outside the projector 500. The object may be, for example, a screen. The optical unit 300 includes a condenser lens 70, a rod integrator 71, a lens unit 72, a display element 73, and a projection lens 74.

The condenser lens 70 condenses the light emitted from the optical device 220. Thereby, the light emitted from the optical device 220 is condensed on the incident end surface of the rod integrator 71.

The rod integrator 71 has, for example, a rectangular prism shape. The light incident on the incident end face of the rod integrator 71 is repeatedly totally reflected inside the rod integrator 71, and is emitted from the emitting end face of the rod integrator 71. The light emitted from the rod integrator 71 has a uniform luminance distribution.

The lens unit 72 has a plurality of lenses. Examples of the plurality of lenses included in the lens unit 72 include a condenser lens and a relay lens. The lens unit 72 guides the light emitted from the rod integrator 71 to the display element 73.

The display element 73 converts light that has passed through the lens unit 72. As a result, an image or video to be projected on an object outside the projector 500 is obtained. The display element 73 is, for example, a digital mirror device (DMD).

The projection lens 74 projects the light converted by the display element 73 to the outside of the projector 500. Thereby, the light converted by the display element 73 can be projected on the target object. The projection lens 74 has one or more lenses. Examples of the lens included in the projection lens 74 include a biconvex lens and a plano-concave lens.

The control unit 400 controls each unit of the optical device 220 and the optical unit 300. The control unit 400 is, for example, a microcomputer or a processor.

FIG. 13 is a perspective view of the projector 500. As shown in FIG. 13, the projector 500 further includes a housing 510. The housing 510 houses the optical device 220, the optical unit 300, and the control unit 400. A part of the projection lens 74 of the optical unit 300 is exposed to the outside of the housing 510.

(Embodiment of lighting device)
FIG. 14 is a schematic configuration diagram of the illumination device 600 according to the present embodiment. As shown in FIG. 14, the lighting device 600 includes an optical device 200 and an optical component 80. Instead of the optical device 200, the optical device 210 described with reference to FIG. 9 can also be used. The optical component 80 is a component for guiding the light emitted from the optical device 200 forward, and is specifically a reflector. The optical component 80 has, for example, a metal film of Al, Ag, or the like, or an Al film having a dielectric layer formed on the surface thereof. A filter 81 may be provided in front of the optical device 200. The filter 81 absorbs or scatters blue light so that the coherent blue light from the excitation light source of the optical device 200 does not directly go out. The lighting device 600 may be a so-called reflector type or a projector type. The lighting device 600 is, for example, a vehicle headlamp.

The present disclosure will be specifically described based on examples. However, the present disclosure is not limited to the following examples.

[Filler particles]
(Samples 1-5)
Filler particles of Samples 1 to 5 were prepared. The filler particles of Sample 1 were made of alumina. The filler particles of sample 2 were made of polystyrene. The filler particles of Sample 3 were made of polymethylmethacrylate (PMMA). The filler particles of Sample 4 were silicone composite particles composed of a core made of silicone rubber and a shell made of a silicone resin other than silicone rubber. The filler particles of sample 5 were made of silicone rubber.

[Adhesiveness of filler particles]
An adhesion test was performed on each of the filler particles of Samples 1-5. The adhesion test was carried out by placing a plurality of filler particles in a petri dish and heating the petri dish for each sample. The heating was performed using a dryer. The heating of the plurality of filler particles was performed at an ambient temperature of 200° C. for 24 hours. The results of the adhesion test are shown in Table 1. After heating the plurality of filler particles, and when the plurality of filler particles adhere to each other to form a lump, the adhesiveness was evaluated as good (indicated by “G”). When the plurality of filler particles did not adhere to each other, the adhesiveness was evaluated as poor (indicated by “NG”). The heating of the plurality of filler particles was also performed at an ambient temperature of 240° C. for 24 hours.

As can be seen from Table 1, the filler particles of Samples 2 to 5 containing the resin material had adhesiveness.

[Light absorption rate of filler particles]
For each of the filler particles of Samples 1 to 5, the absorptance with respect to light having a wavelength of 450 nm and the absorptance with respect to light having a wavelength of 550 nm were measured. An absolute PL quantum yield measuring device (C9920-02G manufactured by Hamamatsu Photonics KK) was used for measuring the absorptance. A petri dish made of synthetic quartz was used for measuring the absorptance. The bottom surface of the petri dish had a circular shape in plan view. The diameter of the bottom surface of the dish in plan view was about 17 mm. The thickness of the petri dish was about 5 mm. The dish was equipped with a lid. The measurement results are shown in Table 2.

In Table 2, filler particles having an absorption rate of 10% or less for light having a wavelength of 550 nm were evaluated to have good heat resistance (indicated by "G"). The filler particles having an absorptance for light having a wavelength of 550 nm of more than 10% and 25% or less were evaluated to have a slightly good heat resistance (indicated by "F"). The filler particles having an absorptivity for light having a wavelength of 550 nm of more than 25% were evaluated as having poor heat resistance (indicated by “NG”).

[Heat resistance of filler particles at 200°C]
Each of the filler particles of Samples 1-5 was heated at ambient temperature of 200° C. for 24 hours. With respect to the filler particles after heating, the absorptance for light having a wavelength of 450 nm and the absorptance for light having a wavelength of 550 nm were measured by the same method as described above. Table 2 shows the results of the measures.

In Table 2, the filler particles having an absorption rate of 10% or less for light having a wavelength of 550 nm were evaluated to have good heat resistance at 200° C. (indicated by “G”). The filler particles having an absorptivity for light with a wavelength of 550 nm of more than 10% and 25% or less were evaluated as having slightly good heat resistance at 200° C. (indicated by “F”). The filler particles having an absorptance for light having a wavelength of 550 nm of more than 25% were evaluated as having poor heat resistance at 200° C. (indicated by “NG”).

[Heat resistance of filler particles at 240°C]
Each of the filler particles of Samples 1-5 was heated at an ambient temperature of 240°C for 24 hours. With respect to the filler particles after heating, the absorptance for light having a wavelength of 450 nm and the absorptance for light having a wavelength of 550 nm were measured by the same method as described above. The measurement results are shown in Table 2.

In Table 2, the filler particles having an absorption rate of 10% or less for light having a wavelength of 550 nm were evaluated to have good heat resistance at 240° C. (indicated by “G”). The filler particles having an absorptance for light having a wavelength of 550 nm of more than 10% and 25% or less were evaluated to have a slightly good heat resistance at 240° C. (indicated by “F”). The filler particles having an absorptance for light having a wavelength of 550 nm of more than 25% were evaluated as having poor heat resistance at 240° C. (indicated by “NG”).

As can be seen from Table 2, the filler particles of Samples 4 and 5 containing silicone rubber or silicone resin had not only excellent adhesiveness but also excellent heat resistance.

[Phosphor precursor]
(Comparative Example 1)
The precursor of the phosphor part of Comparative Example 1 was produced by the following method. First, a crystalline ZnO thin film was formed on the substrate body. A silicon substrate provided with a reflective layer was used as the substrate body. The substrate body had a square shape in plan view. The length of one side of the substrate body in plan view was 5 mm. Phosphor particles were arranged on the ZnO thin film. Next, the phosphor particles were subjected to heat treatment. The heat treatment was performed at an ambient temperature of 200° C. for 10 minutes and then at an ambient temperature of 250° C. for 30 minutes. As a result, a precursor of the phosphor portion of Comparative Example 1 formed on the substrate was obtained. The phosphor was made of Y ₃ Al ₅ O ₁₂ :Ce(YAG). The average particle size of the phosphor particles was 16 μm. The thickness of the precursor was 80 μm. The precursor had a circular shape in plan view. The diameter of the precursor in plan view was 3 mm.

(Comparative example 2)
A precursor for the phosphor portion of Comparative Example 2 was obtained by the same method as in Comparative Example 1 except that the filler particles of Sample 1 were placed on the ZnO thin film together with the particles of the phosphor. In the precursor of the phosphor part of Comparative Example 2, the value of V2/(V1+V2) defined by the total volume V1 of the particles of the phosphor (the total volume of the phosphor) and the total volume V2 of the filler particles is 0. It was 05.

(Example 1)
A precursor of the phosphor part of Example 1 was obtained by the same method as Comparative Example 2 except that the filler particles of Sample 1 were changed to the filler particles of Sample 2.

(Example 2)
A precursor of the phosphor part of Example 2 was obtained by the same method as Comparative Example 2 except that the filler particles of Sample 1 were changed to the filler particles of Sample 3.

(Example 3)
Phosphor part of Example 3 by the same method as Comparative Example 2 except that the filler particles of Sample 1 were changed to the filler particles of Sample 4 and the value of V2/(V1+V2) was adjusted to 0.16. A precursor of was obtained.

(Example 4)
A precursor for the phosphor part of Example 4 was obtained by the same method as Comparative Example 2 except that the filler particles of Sample 1 were changed to the filler particles of Sample 5.

(Example 5)
A precursor for the phosphor part of Example 5 was obtained in the same manner as in Example 4, except that the value of V2/(V1+V2) was adjusted to 0.16.

[Vibration test of precursor of phosphor part]
A vibration test was performed on each of the precursors of the phosphor parts of Comparative Examples 1 and 2 and Examples 1 to 5. First, the precursor of the phosphor portion was set together with the substrate in a chip case (CT100-066 manufactured by Dainichi Trading Co., Ltd.). The chip case had a square pocket in plan view. The length of one side of the pocket in plan view was 6.6 mm. The depth of the pocket was 2.54 mm. Next, the chip case was set in the vibration tester. The chip case was vibrated by a vibration tester. At this time, the amplitude of the chip case was 4.5 mm. The vibration tester converts the rotation of the motor into vibration. Regarding the intensity of vibration, the value of the intensity of vibration at a rotation speed of the motor of 200 rpm was defined as 1, and the value of the intensity of vibration at a rotation speed of the motor of 2500 rpm was defined as 10. The vibration test started at a strength of 1. After that, the strength value was increased by 1 every 20 seconds. The vibration test was terminated 20 seconds after the vibration intensity reached a value of 10. The results of the vibration test are shown in Table 3.

In Table 3, the numerical value of the vibration test shows the strength of vibration when the particles of the phosphor are dropped from the precursor of the phosphor part. However, in Table 3, in the precursor of the phosphor part of Example 5, the particles of the phosphor did not fall off even with the vibration of strength 10.

Furthermore, before and after the vibration test, the surface of the precursor of the phosphor part was observed with a microscope at a magnification of 50 times. As the microscope, a digital microscope VH-5000 manufactured by KEYENCE was used. FIG. 15A shows a microscope image of the precursor of the phosphor part of Example 2 before carrying out the vibration test. FIG. 15B shows a microscope image of the precursor of the phosphor part of Example 2 after the vibration test was performed. From FIG. 15A and FIG. 15B, it can be seen that the phosphor was dropped from the precursor of the phosphor part due to the large vibration. Further, FIG. 16A shows a microscope image of the precursor of the phosphor part of Example 3 before carrying out the vibration test. FIG. 16B shows a microscope image of the precursor of the phosphor part of Example 3 after performing the vibration test. From FIGS. 16A and 16B, it can be seen that the fluorescent substance has fallen off from the precursor of the fluorescent substance portion due to the large vibration.

[Dip test of precursor of phosphor part]
An immersion test was performed on each of the precursors of the phosphor parts of Comparative Examples 1 and 2 and Examples 1 to 5. First, 10 precursors each of the phosphor portions of Comparative Examples 1 and 2 and Examples 1 to 5 were prepared. Each of these precursors was supported by the substrate. Next, the substrate supporting the precursor of the phosphor portion was fixed with a jig. The substrate was set inside the test container. A ZnO crystal growth solution was added to the container. An aqueous solution of zinc nitrate and hexamethylenetetramine was used as a solution for crystal growth. The substrate was taken out of the solution for crystal growth. After the immersion test, the number of substrates from which the precursor of the phosphor part had fallen off was counted. The results of the immersion test are shown in Table 3. When the number of substrates from which the precursor of the phosphor part had fallen off by the immersion test was 0 or more and 3 or less, the result of the immersion test was evaluated as good (indicated by "G"). When this number was 4 or more and 10 or less, the result of the immersion test was evaluated as poor (indicated by "NG").

As can be seen from Table 3, the phosphor precursors of Examples 1 to 5 provided with the filler particles containing the resin material have a higher phosphor content from the substrate than the phosphor precursors of Comparative Examples 1 and 2. Was completely suppressed.

[Wavelength conversion member]
Next, a wavelength conversion member was produced using each of the precursors of the phosphor parts of Examples 2, 3, and 5. Specifically, a crystalline ZnO matrix was formed on the ZnO thin film by the solution growth method. An aqueous solution of zinc nitrate and hexamethylenetetramine was used as a solution for crystal growth. Thereby, the wavelength conversion members of Examples 2, 3, and 5 were obtained.

Next, the wavelength conversion member of Example 2 was cut, and the cut surface was observed with a scanning electron microscope (SEM). As the SEM, S-4300 manufactured by Hitachi High-Technologies Corporation was used. FIG. 17A shows a SEM image of a cross section of the wavelength conversion member of Example 2. FIG. 17B is an enlarged view of the filler particles shown in FIG. 17A. As can be seen from FIG. 17A, in the wavelength conversion member, the filler particles adhered to the phosphor. As can be seen from FIG. 17B, some of the filler particles contained in the wavelength conversion member were adhered to each other. Each of the plurality of filler particles adhered to each other maintained the shape of the particles.

Like the wavelength conversion member of Example 2, the wavelength conversion member of Example 3 was cut, and the cut surface was observed by SEM. As the SEM, a tabletop microscope Miniscope TM4000 Plus manufactured by Hitachi High-Technologies Corporation was used. FIG. 18A shows a SEM image of a cross section of the wavelength conversion member of Example 3. FIG. 18B is an enlarged view of the filler particles shown in FIG. 18A. FIG. 18C is an enlarged view of another filler particle shown in FIG. 18A. As can be seen from FIG. 18A, in the wavelength conversion member, the filler particles adhered to the phosphor. As can be seen from FIG. 18B, among the plurality of filler particles contained in the wavelength conversion member, some filler particles were adhered to each of the two particles of the phosphor. As can be seen from FIG. 18C, some of the plurality of filler particles included in the wavelength conversion member were adhered to the phosphor particles and the substrate, respectively.

[Emission efficiency of wavelength conversion member]
Luminous efficiency was measured for each of the wavelength conversion members of Examples 2, 3, and 5. Luminous efficiency was measured using a multi-channel spectrometer (MCPD-9800 manufactured by Otsuka Electronics Co., Ltd.) and an integrating sphere manufactured by Labsphere. The wavelength of the excitation light of the LD used was 445 nm. The energy density of the excitation light was ² W/mm ² . Table 4 shows the measurement results.

Next, each of the wavelength conversion members of Examples 2, 3, and 5 was heated. The wavelength conversion member was heated at an ambient temperature of 240° C. for 24 hours. The luminous efficiency of the heated wavelength conversion member was measured by the method described above. Table 4 shows the measurement results.

As can be seen from Table 4, the wavelength conversion members of Examples 2, 3, and 5 all had good luminous efficiency. In particular, the wavelength conversion members of Examples 3 and 5 maintained good luminous efficiency even after being heat-treated.

The wavelength conversion member 100 (110, 120, 130, 140) of the present disclosure includes a matrix 21 containing an inorganic material, a phosphor 22 embedded in the matrix 21, and a filler embedded in the matrix 21 and containing a resin material. And particles 23.

Since the filler particles 23 include the resin material, the filler particles 23 can be adhered to the phosphor 22. Similarly, the filler particles 23 can be adhered to the substrate 10 used when manufacturing the wavelength conversion member. Therefore, the filler particles 23 can fix the phosphor 22 to the substrate 10. As a result, it is possible to prevent the phosphor 22 from falling off the substrate 10 before the matrix 21 is formed. That is, in the wavelength conversion member, the fluorescent substance 22 is prevented from falling off.

The wavelength conversion member may further include the substrate 10 that supports the matrix 21, and the filler particles 23 may be located between the phosphor 22 and the substrate 10. As a result, the fluorescent substance 22 is prevented from falling off in the wavelength conversion member.

In the wavelength conversion member, the substrate 10 includes at least one selected from the group consisting of stainless steel, a composite material of aluminum and silicon carbide, a composite material of aluminum and silicon, a composite material of aluminum and carbon, and copper. You can leave. As a result, the thermal expansion coefficient of the substrate 10 is small. Therefore, even if the temperature of the substrate 10 rises due to the use of the wavelength conversion member, the wavelength conversion member has high reliability.

In the wavelength conversion member, the matrix 21 may include an inorganic crystal. As a result, the matrix 21 has excellent heat dissipation.

In the wavelength conversion member, the inorganic crystal may include zinc oxide. Thereby, the matrix 21 has a more excellent heat dissipation property.

In the wavelength conversion member, the zinc oxide may be oriented along the c-axis. Thereby, the matrix 21 has a more excellent heat dissipation property.

In the wavelength conversion member, the resin material may include a thermoplastic resin. As a result, the fluorescent substance 22 is prevented from falling off in the wavelength conversion member.

In the wavelength conversion member, the resin material may include a thermosetting resin. As a result, the fluorescent substance 22 is prevented from falling off in the wavelength conversion member.

In the wavelength conversion member, the filler particles 23 may have rubber elasticity. As a result, the contact area between the filler particles 23 and the phosphor 22 is wide. Therefore, the filler particles 23 can sufficiently fix the phosphor 22. As a result, in the wavelength conversion member, the phosphor 22 is further suppressed from falling off.

In the wavelength conversion member, the resin material may include a polymer compound having a siloxane bond. Thereby, the filler particles 23 have excellent heat resistance.

In the wavelength conversion member, the filler particles 23 may have the core 30 and the shell 31 that covers the core 30. Thereby, the filler particles 23 have excellent dispersibility.

In the wavelength conversion member, the filler particles 23 may have a surface modified with a functional group. Thereby, the filler particles 23 have excellent dispersibility.

In the wavelength conversion member, the absorptance of the filler particles 23 for light with a wavelength of 550 nm is preferably 25% or less. As a result, the wavelength conversion member has high luminous efficiency.

In the wavelength conversion member, the value of V2/(V1+V2) defined by the volume V1 of the phosphor 22 and the total volume V2 of the filler particles 23 may be 0.05 or more and 0.16 or less. As a result, in the wavelength conversion member, the phosphor 22 is further suppressed from falling off.

The optical device 200 (210, 220) includes a wavelength conversion member 100 (110, 120, 130, 140) and an excitation light source 40 that irradiates the wavelength conversion member with excitation light. As a result, the fluorescent substance 22 is prevented from falling off in the wavelength conversion member included in the optical device.

The projector 500 includes the above wavelength conversion member. This prevents the fluorescent substance 22 from falling off in the wavelength conversion member included in the projector 500.

A phosphor 22 and filler particles 23 containing a resin material are arranged on the substrate 10. The phosphor 22 is fixed to the substrate 10 by the filler particles 23. The matrix 21 containing an inorganic material is formed so that each of the filler particles 23 and the phosphor 22 is embedded in the matrix 21. Thereby, the wavelength conversion member can be manufactured.

Thereby, the phosphor 22 is fixed to the substrate 10 by the filler particles 23. Therefore, it is possible to prevent the phosphor 22 from falling off the substrate 10 before the matrix 21 is formed.

In this manufacturing method, the phosphor 22 may be fixed to the substrate 10 by adhering the filler particles 23 to each of the phosphor 22 and the substrate 10. Thereby, the phosphor 22 can be easily fixed to the substrate 10.

In this manufacturing method, the filler particles 23 may be adhered to each of the phosphor 22 and the substrate 10 by heating the filler particles 23. Thereby, the phosphor 22 can be easily fixed to the substrate 10.

The wavelength conversion member of the present disclosure includes, for example, general lighting devices such as ceiling lights; special lighting devices such as spotlights, stadium lighting, and studio lighting; vehicle lighting devices such as headlamps; projectors, head-up displays, and the like. Projection device; Medical or industrial endoscope light; Imaging device such as digital camera, mobile phone, smartphone; Personal computer (PC) monitor, notebook personal computer, TV, personal digital assistant (PDX), smartphone It can be used as a light source in liquid crystal display devices such as tablet PCs and mobile phones.

10 substrate 11 substrate body 12 thin film 20 phosphor part 21 matrix 22 phosphor 23 filler particle 30 core 31 shell 40 excitation light source 100, 110, 120, 130, 140 wavelength conversion member 200, 210, 220 optical device 500 projector 600 illumination device

Claims (19)

1. A matrix containing an inorganic material,
   A phosphor embedded in the matrix,
   A plurality of filler particles embedded in the matrix and containing a resin material,
   A wavelength conversion member provided with.
2. Further comprising a substrate supporting the matrix,
   The wavelength conversion member according to claim 1, wherein the plurality of filler particles are located between the phosphor and the substrate.
3. The substrate includes at least one selected from the group consisting of stainless steel, a composite material of aluminum and silicon carbide, a composite material of aluminum and silicon, a composite material of aluminum and carbon, and copper. The wavelength conversion member described.
4. The wavelength conversion member according to claim 1, wherein the matrix contains an inorganic crystal.
5. The wavelength conversion member according to claim 4, wherein the inorganic crystal contains zinc oxide.
6. The wavelength conversion member according to claim 5, wherein the zinc oxide is c-axis oriented.
7. The wavelength conversion member according to claim 1, wherein the resin material contains a thermoplastic resin.
8. The wavelength conversion member according to claim 1, wherein the resin material includes a thermosetting resin.
9. The wavelength conversion member according to claim 1, wherein the plurality of filler particles have rubber elasticity.
10. The wavelength conversion member according to claim 1, wherein the resin material includes a polymer compound having a siloxane bond.
11. The wavelength conversion member according to any one of claims 1 to 10, wherein the plurality of filler particles have a core and a shell covering the core.
12. The wavelength conversion member according to any one of claims 1 to 11, wherein the plurality of filler particles have a surface modified with a functional group.
13. The wavelength conversion member according to any one of claims 1 to 12, wherein an absorptivity of the plurality of filler particles with respect to light having a wavelength of 550 nm is 25% or less.
14. The value of V2/(V1+V2) defined by the volume V1 of the phosphor and the total volume V2 of the plurality of filler particles is 0.05 or more and 0.16 or less. The wavelength conversion member according to the item.
15. The wavelength conversion member according to any one of claims 1 to 14,
    An excitation light source that irradiates the wavelength conversion member with excitation light,
    Optical device equipped with.
16. A projector comprising the wavelength conversion member according to claim 1.
17. Fixing the phosphor to the substrate with a plurality of filler particles containing a resin material,
    Forming the matrix so that the plurality of filler particles and the phosphor are embedded in a matrix containing an inorganic material,
    A method of manufacturing a wavelength conversion member, comprising:
18. The manufacturing method according to claim 17, wherein fixing the phosphor to the substrate includes adhering the plurality of filler particles to the phosphor and the substrate.
19. Bonding the plurality of filler particles to the phosphor and the substrate includes bonding the plurality of filler particles to the phosphor and the substrate by heating the plurality of filler particles, Item 19. The manufacturing method according to Item 18.

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